A bandgap reference circuit provides a constant voltage over a temperature range and is commonly used to supply a reference voltage that is compared with other voltages within an integrated circuit. A bandgap reference circuit typically combines two potentials, one having a positive temperature coefficient and another having a negative temperature coefficient to provide the reference voltage.
A startup circuit is commonly incorporated with the bandgap reference circuit to ensure the bandgap reference circuit starts. The startup circuit functions to set the proper operational state during power up of the bandgap reference circuit. However, in some instances, the bandgap reference circuit may not “wake up” properly after power up or after an external noise disturbance. For example, under certain process voltage temperature (PVT) conditions, where the power supply sags or where the bandgap reference voltage collapses due to an external noise disturbance, the bandgap reference voltage may not reliably ramp up to the expected reference voltage.
It is within this context that the embodiments arise.